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Developing new methods in x-ray microscopy, with applications in biology and materials science

Biography

Chris Jacobsen is an Argonne Distinguished Fellow at Argonne National Laboratory, and a Professor of Physics & Astronomy at Northwestern University. He is a Fellow of the American Association for the Advancement of Science, the American Physical Society, and the Optical Society of America. He is the recipient of a Presidential Faculty Fellow Award (White House/National Science Foundation), the International Dennis Gabor Award, and the Kurt Heinrich Award.

His group’s research is focused on developing new methods in x-ray microscopy, and applying them to interesting problems in biology, environmental science, and materials science. Using either diffractive optics (like Fresnel zone plates fabricated using electron beam lithography), or lensless methods where iterative phase retrieval methods are used to reconstruct an image from a coherent diffraction pattern, images with a spatial resolution of 20 nm or better can be obtained. In absorption contrast, one can combine imaging with spectroscopy to study chemical speciation at the nanoscale, or one can use fluorescence detection to study trace element distributions with parts-per-billion sensitivity. We are also developing detectors and image reconstruction algorithms that can be used to obtain quantitative phase contrast images with hard X rays, and thus put elemental distributions into their ultrastructural context. Finally, we are interested in understanding the limitations that radiation damage presents to x-ray microscopy studies, and in developing both cryo instrumentation and sample preparation methods to mitigate those limitations.